Data Flow Diagrams Notations

DFD Data Flow Diagrams A data flow diagram is a graphical technique that depicts information flow and the transforms that are applied as data move from input to output. The data flow diagram is also known as 'data flow graph'. Various symbols are used to depict the data from one level to another level. The data flow diagram must be used to represent the system or software at any level of abstraction. In fact data flow diagram may partitioned into the levels that represent increasing information flow for functional modeling as information on flow modeling. In doing so it satisfies the second operational analysis principle i.e., creating a functional model.

 

Notation
Logical data flow diagrams can be completed using only four simple notations, i.e. special symbols or icons and the annotation that associates them with a specific system the Yourdon approach is used.

1.DataFlow

Data move in a specific direction from an origin to a destination in the form of a document. The data flow is a "packet of data".

2.Process

People procedure or devices that use or produce data. The physical component is not identified.

3.Source or Destination

External sources or destinations of data interact with the system but are outside its boundary.

4.Data Store

Here data are stored or referenced by process in the system.